# Operating Systems > Unix/Linux Usage of this Command

## sripri

What is the command ipcrm used for in UNIX operating system. Is it an administrative command or not? Kindly someone let me know the syntax and usage of this command.

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## RajivPrasad

ipcrm: This command is used for removing message queue, semaphore set, or shared memory identifiers.

The general syntax of this command is:

ipcrm [-m shared_memory] [-M shared_memory_key] [-q message_queue] [-Q
         message_key] [-s semaphore_ID] [-S semaphore_key]
where:
  -m shared_memory
      Removes the shared memory identifier shared_memory. The shared memory segment and data structure associated with shared_memory are also
removed after the last detach operation.

  -M shared_memory_key 
     Removes the shared memory identifier, created with key
     shared_memory_key. The shared memory segment and data structure associated with it are also removed after the last detach.

  -q message_queue
      Removes the message queue identifier message_queue and the message
      queue and data structure associated with it.

  -Q message_key
      Removes the message queue identifier, created with key message_key, and the message queue and data structure associated with it.

  -s semaphore_ID
      Removes the semaphore identifier semaphore_ID and the set of semaphores and data structure associated with it.

  -S semaphore_key
      Removes the semaphore identifier, created with key semaphore_key, and
      the set of semaphores and data structure associated with it.

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